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84 lines
2.2 KiB
Plaintext
84 lines
2.2 KiB
Plaintext
/*
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* splitbits - split an integer into list on bit boundardies of a fixed size
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*
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* Copyright (C) 2018,2023 Landon Curt Noll
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*
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* Calc is open software; you can redistribute it and/or modify it under
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* the terms of the version 2.1 of the GNU Lesser General Public License
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* as published by the Free Software Foundation.
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*
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* Calc is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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* Public License for more details.
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*
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* A copy of version 2.1 of the GNU Lesser General Public License is
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* distributed with calc under the filename COPYING-LGPL. You should have
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* received a copy with calc; if not, write to Free Software Foundation, Inc.
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* Under source code control: 2006/06/07 14:10:11
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* File existed as early as: 2006
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*
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* chongo <was here> /\oo/\ http://www.isthe.com/chongo/
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* Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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*/
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/*
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* setup splitbits errors
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*/
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static E_SPLITBITS_1, E_SPLITBITS_2, E_SPLITBITS_3;
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if (! iserror(E_SPLITBITS_1)) E_SPLITBITS_1 = newerror("1st argument to splitbits must be an integer");
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if (! iserror(E_SPLITBITS_2)) E_SPLITBITS_2 = newerror("2nd argument to splitbits must be an integer");
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if (! iserror(E_SPLITBITS_3)) E_SPLITBITS_3 = newerror("2nd argument must be an integer > 0");
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/*
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* define splitbits function
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*/
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define splitbits(x, b)
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{
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local ret; /* list to return */
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local mask; /* 2^b-1 */
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local x_is_reg = 0; /* true if x < 0 */
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/* firewall */
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if (! isint(x)) {
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return error(E_SPLITBITS_1);
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}
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if (! isint(b)) {
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return error(E_SPLITBITS_2);
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}
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if (b <= 0) {
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return error(E_SPLITBITS_3);
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}
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/* special case: x == 0 */
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if (x == 0) {
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return list(0);
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}
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/* setup for splitting x */
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ret = list();
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mask = 2^b-1;
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if (x < 0) {
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x_is_reg = 1;
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x = abs(x);
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}
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/* split x */
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while (x > 0) {
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printf("%d %x\n", size(ret), x);
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if (x_is_reg) {
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append(ret, xor(x & mask, mask));
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} else {
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append(ret, x & mask);
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}
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x >>= b;
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}
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/* return list */
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return ret;
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}
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